Simplify the following expression: $3\sqrt{75}$.
Answer: First, try to factor a perfect square out of the radical. $= 3\sqrt{75}$ $= 3\sqrt{25 \cdot 3}$ Separate the radical and simplify. $= 3\sqrt{25} \cdot \sqrt{3}$ $= 3 \cdot 5 \cdot \sqrt{3}$ $= 15\sqrt{3}$